The present invention relates to a method of transmitting digital data, particularly for digital video signals, wherein an analog signal is converted into a digital signal, wherein groups of values are processed in a source coder and then fed by a channel coder to a transmission channel, and wherein the groups of values travel from the transmission channel through a channel decoder to a source decoder.
According to the 1980 dissertation paper by W. Mauersberger at the Technical University of Aachen, entitled "Adaptive Transformationskodierung von digitalisierten Bildsignalen" [Adaptive Transformation Coding of Digitalized Video Signals], the problems encountered in digital communication involve the processing and transmission of the digital data. Source coding is employed to reduce the volume of data transmitted over one data channel (page 1 of the dissertation). The reduction of data is not realized by prediction or transformation but by quantizing of a preprocessed signal (page 67 of the dissertation). Before the transmission, a block, hereinafter called a matrix, of transformed values, hereinafter called spectral values or spectral coefficients, is classified. The classification is made in such a manner that, corresponding to their significance, a selected group of spectral values, which may be a row, a column, parts of a row or parts of a column or a combination of parts of a column and/or parts of a row, are transmitted. A total of seven classes are provided (pages 154 et seq.) Then the address of the class is transmitted and thereafter the quantized spectral values are transmitted. The drawback of this system is that redundant values are also transmitted.
Another method disclosed in FIG. 5 of European Offenlegungschrift [patent application published without examination] No. 0,084,270, involves a zigzag scan with length of run coding. In this case, the matrix of spectral value is scanned diagonally beginning at the top left. The delay time indicates how many values have been transferred altogether before the run is terminated. Here again the drawback of the system is that redundant values in the path of the scanner are also transmitted.